Knock on Turning

[whitenemesis]

Ever since having my front discs & pads replaced I've had a faint "knock" from the front of the car. It only happens when I turn more than ~45deg. and only once per direction. By that I mean if I turn right it knocks, if I turn right again, nothing.. until I turn left then "knock"!
At first I thought perhaps a stone rattling back and forth on the undertray, or even a forgotten tool from the service work! But it does seem to be getting louder, of course could be just me becoming hyper-sensitive!!
Otherwise the car drives / handles fine... Any ideas?

 

[television]

Normally an anti roll bar bush or link when the steering and suspension is at an unsual loading

 

[Aussie Nick]

I second Malcolm.I dont think you have anything to worry about.Alot of cars do it.

 

[whitenemesis]

Thanks guys.

Well my car didn't used to do it, so something has changed, worn? Perhaps another call on Service-Plus?

 

[Aussie Nick]

Maybe not a bad idea as it will give you a more technical explanation (I Hope) and may allay your concerns. I stiil dont think you should be alarmed. Entropy is always active so all things gradually change over time.

 

[wireman]

Maybe its what my dad once had, loose steering rack mounting bolts, just loose enough to clonk as you describe occasionaly, The fault persisted for months until the loose nuts were found and the racks mounting lugs were by then damaged beyond repair so it had to have a new rack.

 

[whitenemesis]

Update

Took my car to the dealers on Thursday, after a drive round the carpark the tech diagnoses torque control arm bushes, stock items so straight into the workshop. 1hr later was told the bushes looked fine, it's the strut upper mountings that have failed Parts ordered.

Back to dealer this morning, left the car for 4hrs. Whent to collect the car and was told strut mounts replaced, torque control arm bushes replaced, knocking still there.........

While the sound is a "knock" it is also has a "creak" element. I still think it is more to do with the steering gear in some way.

 

[television]

Bottom ball joints

 

[whitenemesis]

Bottom ball joints

As in track rod ends?

 

[television]

As in track rod ends?

Yes also them as well the bottom swivel is a ball joint.

Roll bar links can knock when turning 45 degrees owing to the unusual angles in the suspension

 

[whitenemesis]

I'm assuming these have been replaced, with the torque control arm bushes?

I've never experienced knocking from worn track rod ends, I've replaced many on previous vehicles...

 

[tsanders]

I actually go for wishbone bushes. Mine is doing the same.

I had the ARB rubbers and drop-links replaced and this has eliminated a different noise (I can best describe it as snooker balls going into the pocket as you go over bumps/pot holes); also had bottom ball joints done (no noticable noise changes) but worn all the same.

 

[whitenemesis]

Other suggestions have been steering coupling wear (this was Milton Keynes MB suggestion) or possibly the steering thrust washer(?) apparently these are PLASTIC on some racks, depending on chassis No. The replacement part is aluminium..

Both these conditions can lead to a clunk on changing direction

 

[whitenemesis]

Update!!

Spent another 6hrs at MB Swindon today.

Front of car dismantled to reveal the chasis rails and the cross-member plus crush blocks. All bolts loosened off, mating surfaces coated with some sort of waxy oil (chasis rust proofer I think) and all torqued back up.

Out for test drive..... silence! The creak, crack, has gone

A big thank you to Mark the MB tech who just wouldn't rest until he found and cured the problem. All-in-all he must have spent about 10hrs tracking this down.

Great service MB Swindon

 

[Rory]

Did the dealer / ServicePlus cover this without a murmur?

 

[whitenemesis]

The dealer did all the work without hesitation. Service Plus did question the relevance of some of the work but the dealer said it was required to eliminate possible causes.

No charge!

 

[Rory]

Thank goodness for that!

 

[occurs_to_me]

Hi, mine is an E270 CDI.
Has a"knock" when turned almost full way to left.
Will knock a little on return to centre.
Will knock when turned almost full way to right.
All knocks when stationary or moving off.
Does this sound like the problem you had whitenemesis?

 

[whitenemesis]

No, my knock was only when on the move. Yours could be suspension bushes or perhaps loose steering rack mountings?

 

[occurs_to_me]

Turns out it was that the Steel Sump protector was loose / bent and was catching on the steering mechanism.